Breast Cancer Genetics

Cecelia Bellcross, PhD: As a cancer genetics specialist who has worked in this field for 25 years, one of the most important things for individuals to consider if they are thinking about genetic testing and post-test counseling about their results from a specialist in the field. It is not a simple blood test. There are a lot of complicating factors. And the individual undergoing the testing needs to understand thoroughly what the risks, benefits and limitations are. And how we interpret those results and have the opportunity to have all of their questions answered prior to having that blood drawn. The greatest benefit or under circumstances where an individual in a family tests positive for a mutation in BRCA 1 or 2 that has had cancer themselves, then we know what that means for the rest of the family. So that individual’s children have a 50/50 chance to have inherited that mutation. If they did not inherit that mutation then they have no greater risk for cancer, breast or ovarian cancer, related cancers, beyond someone in the general population. So the panel testing allows for multiple genes that have been associated with cancer in the family, to be tested for it once. And while that sounds like a great idea, the problem is, is that many of the genes on these panels, we know very little about. So it is somewhat of an instance of the technology being there, we can test for it so why not? Without necessarily having all the information to appropriately interpret those tests. There is also a much higher likelihood that you test for a lot of genes, you’re going to find changes in the genes that you don’t know how to interpret. People also have to consider though that it’s not a crystal ball, we can’t tell somebody exactly what their cancer risks are. Not everyone who inherits mutation will develop cancer over the course of their lifetime. There are limits to what we can do to prevent some cancers and there is also consideration of the emotional ramifications and family ramification of learning that one inherits the hereditary cancer gene.